This invention pertains generally to radiation detectors and more specifically to radiation detectors providing a digital signal indicative of the angle of incidence of a radiation beam with the detector.
The optical direction of arrival sensor disclosed in the present application is closely related to the optical direction of arrival sensor disclosed in the application entitled "Direction of Arrival Sensor", filed on even date herewith by D. S. Dunavan et al., Ser. No. 174,059 and assigned to the assignee of this application. The disclosure therein is incorporated herein by reference.
The optical direction of arrival sensor in the co-pending application discloses a top mask with one slit or a plurality of parallel slits through it. Incident radiation passes through a slit and forms a rectangle or bar of radiation on a flat detector array which embodies Gray code encoding means. The detector array is arranged in rows, each row being perpendicular to the bar of radiation. As is more fully explained in the co-pending application, each of the rows generates an electrical signal which is a function of the location of the bar on the row. This electrical signal is then processed to yield a digital bit of information, that is a 1 or a 0. The combination of each of these bits from each row produces the digital angle-of-arrival word which uniquely indicates where the radiation bar falls on the detector array. This angle-of-arrival word, in turn, bears a direct relationship to the angle of incidence of the incoming radiation with the detector and can be processed to yield that angle.
While the apparatus disclosed in the co-pending application operates successfully, our contribution is an improvement over the prior art which results in improved sensitivity of the optical direction of arrival sensor by increasing the effective aperture of the slit or slits. The improved optical direction of arrival sensor also permits operation of the sensor with lower optical intensities than previously possible, while providing uniform sensitivity throughout the entire field of view. These, and other advantages over the prior art will become clear as the description proceeds.